3.11-3.13 Quiz Flashcards
What type of movement occurs in microwave radiation? Why?
Rotational; This is due to the interaction of the dipole of the molecules interacting with the electromagnetic field of the microwave photons.
What type of movement occurs in infrared radiation?
Vibrational
What type of movement occurs in ultraviolet/visible radiation?
Translational
Spectroscopy
Study of how matter interacts with electromagnetic radiation
If you have a long wavelength, then you have _______ energy. If you have a short wavelength, then you have _______ energy.
Low; high
If you have a long wavelength, then you have _______ frequency. If you have a short wavelength, then you have _______ frequency.
Low; high
Put the three types of movement(translational, vibrational, rotational) in order from least to most energy used.
Rotational, vibrational, translational
Translational movement
Movement from one place to another. This takes the most energy.
Rotational movement
Spinning in place. This is the least amount of energy because spinning it doesn’t take much energy compared to vibrational where the bonds are elongated to vibrate.
Vibrational movement
vibrating/moving in place. This takes the “middlest” amount of energy because the particles are being stretched and bended while moving in place which takes more energy than spinning.
In infrared radiation, what type of atoms vibrate at higher frequencies?
Lighter atoms and stronger bonds
What is one of the most important things that ultraviolet-visible radiation is associated with?
Transitions in electronic energy levels/ when electrons move from their ground state to a higher energy “excited” state.
What does a spectrophotometer do?
You use it to measure the amount of light leaving a sample and comparing it to the amount of the light that entered the sample
Two samples of copper (II) sulfate were analyzed using visible light spectroscopy. Sample One absorbed twice as much light as Sample Two.
a) What can you deduce about the concentrations of the two solutions?
b) What must be true of the solutions in order to get results from this type of spectroscopy?
c) Describe the type of changes that occur within the molecule during the process of UV-Vis spectroscopy.
a) The concentration of sample 1 was double the concentration of sample 2.
b) They must have a color because if they were clear they wouldn’t be able to absorb anything.
c) Energy must be absorbed (causing electrons to move to an excited state) and then emitted (the electrons fall to a lower energy state).
How are absorbance and concentration related?
They are directly related; if one doubles then the other one does too
How could one molecule absorb ultraviolet light but not visible light and another could absorb ultraviolet and visible?
Because one could not produce transitions between energy levels through visible light
What is an approximate number for the wavelength of visible light?
Any number in the 100s
Photoelectric effect
When light shines on the surface of metal and electrons can be ejected from the surface
Photo
Electrons being ejected through light
Threshold frequency
- Definition
- What happens if the frequency used is higher than the threshold frequency?
The amount of energy needed to remove an electron.
If a frequency is higher than the threshold frequency then the electrons will be ejected with more kinetic energy.
Binding energy
How tightly the electrons are being held in the atom
What does a high binding energy mean?
That the electrons are closer to the nucleus or that the nucleus has a higher charge.
Threshold wavelength
- Definition
- What happens if the frequency used is lower than the threshold frequency?
The max amount of energy needed to eject an electron.
Anything shorter than the max will have enough energy to eject the electrons.
What relationship does energy have with frequency? Wavelength?
Energy is directly related to frequency and wavelength is inversely related.
